Hi everyone! I'm making a Space Core costume for a party. It doesn't have to be absolutely amazing, so I was planning on making it out of 2 plastic bowls and then crafting the extra bits on. I'll be wearing it like a motorbike helmet, with a hole for my neck and a faceplate. I've got all the guidelines out.

Space core looks like this, by the way:

The one thing I am worried about is that it'll roll about on my head, because obviously I'm not bowl-shaped. Does anyone have any tips on what to put inside to make it more secure?

You could get some upholstery foam, the stuff that's used for sofa cushions, if you've got a dunelm mill near you it's where I source my foam from.

You could make a sort of shaped motorbike helmet inside so the foam fills the gap between your head and the plastic walls this should stop it rocking about and give it a tight fit. You can get a fair amount of different thicknesses, up to a few inches thick, so it should be perfect.

When I had to wear a top hat that was far too big for me for a show, I wore a pair of bunny ears (with wire in the ears) and packed the hat with loads of kitchen roll. It worked really well and wasn't too hot. No idea how this would be around your whole head though...